Problem: The Rockers made a CD with $9$ songs on it. Their CD had $4$ fewer songs than the CD made by Dustin Beemer. How many songs are on Dustin Beemer's CD?
${\text{The Rockers' songs}} + {4} = {\text{Dustin Beemer's songs}}$ ${9} + {4} = {\Box}$ Dustin Beemer's CD has ${13}$ songs.